[codeconsole]

Why

The console links its webjars at <contextPath>/webjars/..., served by Spring Boot's classpath
mapping. An application that mirrors its static files to a CDN has no way to put these there too.

The only lever today is webjars.enabled = false, which is a much bigger step than the question
deserves: exclude four jars, supply jQuery, Bootstrap and Bootstrap Icons yourself, and maintain a
layout to do it — all to change where bytes are fetched from, not which files or versions.

What

grails.plugin.console.webjars.baseUrl replaces the base for every link the plugin emits, the
CodeMirror import map included:

grails:
    plugin:
        console:
            webjars:
                baseUrl: 'https://cdn.example.com/webjars'

The version in each URL is still resolved from the runtime classpath, so this stays compatible with
an application overriding a webjar version. Unset, the default remains <contextPath>/webjars and
nothing changes.

WebjarVersions.url(contextPath, name, file, defaultVersion = null) builds the URL. It keeps the
build-time default-version fallback the generator already had for CodeMirror, and returns null
for a webjar that is not on the classpath, so a caller can leave the tag out rather than emit one
with a null version in it. The gulp fragments (_webjarsCss.gsp, _webjarsJs.gsp,
_webjarsModules.gsp) now generate through it, which also removes the repeated
${request.contextPath}/webjars/... from 13 import-map entries.

This is deliberately narrower than webjars.enabled = false, and the two compose: an application
that wants to supply its own copies still turns the tags off, and one that just wants them served
from elsewhere sets a base.

Tests

WebjarVersionsSpec covers the URL shape under a context path, the empty and null context path,
the default-version fallback, classpath precedence over that fallback, and the null for an absent
webjar. Full plugin suite: 47 tests, all passing.